FIG. 1 is a schematic of a containment building 36 that houses a reactor pressure vessel 42 with various configurations of fuel 41 and reactor internals for producing nuclear power in a related art economic simplified boiling water reactor (ESBWR). Reactor 42 is conventionally capable of producing and approved to produce several thousand megawatts of thermal energy through nuclear fission. Reactor 42 sits in a drywell 51, including upper drywell 54 and a lower drywell 3 that provides space surrounding and under reactor 42 for external components and personnel. Reactor 42 is typically several dozen meters high, and containment building 36 even higher above ground elevation, to facilitate natural circulation cooling and construction from ground level. A sacrificial melt layer 1, called a basemat-internal melt arrest and coolability device, is positioned directly below reactor 1 to cool potential falling debris, melted reactor structures, and/or coolant and prevent their progression into a ground below containment 36.
Several different pools and flowpaths constitute an emergency core coolant system inside containment 36 to provide fluid coolant to reactor 26 in the case of a transient involving loss of cooling capacity in the plant. For example, containment 36 may include a pressure suppression chamber 58 surrounding reactor 42 in an annular or other fashion and holding suppression pool 59. Suppression pool 59 may include an emergency steam vent used to divert steam from a main steam line into suppression pool 59 for condensation and heat sinking, to prevent over-heating and over-pressurization of containment 36. Suppression pool 59 may also include flow paths that allow fluid flowing into drywell 54 to drain, or be pumped, into suppression pool 59. Suppression pool 59 may further include other heat-exchangers or drains configured to remove heat or pressure from containment 36 following a loss of coolant accident. An emergency core cooling system line and pump 10 may inject coolant from suppression pool 59 into reactor 42 in order to make up lost feedwater and/or other emergency coolant supply.
As shown in FIG. 1, a gravity-driven cooling system (GDCS) pool 37 can further provide coolant to reactor 42 via piping 57. A passive containment cooling system (PCCS) pool 65 may condense any steam inside containment 36, such as steam created through reactor depressurization to lower containment pressure or a main steam line break, and feed the condensed fluid back into GDCS pool 37. An isolation cooling system (ICS) pool 66 may take steam directly at pressure from reactor 42 and condense the same for recirculation back into reactor 42. These safety systems may be used in any combination in various reactor designs, each to the effect of preventing overheating and damage of core 41, reactor 42 and all other structures within containment 36 by supplying necessary coolant, removing heat, and/or reducing pressure. Several additional systems are typically present inside containment 36, and several other auxiliary systems are used in related art ESBWR. Such ESBWRs are described in “The ESBWR Plant General Description” by GE Hitachi Nuclear Energy, Jun. 1, 2011, incorporated herein by reference in its entirety, hereinafter referred to as “ESBWR.”